Protective caps, commonly referred to as weather caps or rain caps, are frequently used with the vertical exhaust pipes of construction or off-road equipment to prevent rain, snow and other materials from entering the exhaust pipe during periods of non-operation. The typical protective cap is hinged to the upper end of the exhaust pipe and is counterweighted to the closed position. On operation of the engine, the increase of pressure in the exhaust pipe will move the cap to the open position.
The conventional pressure responsive cap is subject to vibration of the engine and/or vehicle which induces fatigue in the components of the cap, with the result that the cap may have a limited life of service. The conventional cap is also noisy during engine idling due to the impact of the cap on the clamp and/or exhaust pipe.
In an attempt to reduce noise from the cap, it has been proposed, as described in U.S. Pat. No. 3,523,499 to provide a stop for the cover or lid, so that the lid will be spaced slightly out of contact with the outer end of the exhaust pipe when it is in the closed position. To provide this function, the aforementioned patent includes a clamping ring that is attached to the outer end of the exhaust pipe and a curved crank leg extends upwardly from the clamping ring to a location beyond the outer end of the exhaust pipe. Pivoted to the outer end of the crank leg is an arm which supports a cover or lid, and the arm carries a stop pin which engages a plate mounted on the upper end of the crank leg. With the construction as shown in U.S. Pat. No. 3,523,499, engagement of the stop pin with the plate will space the cover out of contact with the end of the exhaust pipe, when the cover is in the closed position, to thereby reduce vibrational rattling.